The present invention relates to a mechanical transmission device for the frictionless guidance of the pistons of a variable displacement engine.
The mechanical transmission device according to the present invention consists in improving the device which makes it possible to vary, while they are in operation, the working volumetric displacement and/or working volumetric ratio of the piston engines described in French patent application No. 97 05943 in the name of the applicant.
The mechanical transmission device according to the invention has the advantage of making each part of the variable displacement engine easier to machine.
Finally, the mechanical transmission device offers an original solution to limiting friction between the piston and the engine block.
The mechanical transmission device for a variable displacement engine according to the present invention comprises a piston secured at its lower part to a rack collaborating:
On the one hand, with a rolling-bearing guide device, consisting of at least one roller which provides frictionless guidance of said rack on the engine block and of a gearing device which allows the displacement of said roller with respect to te piston to be synchronized,
And on the other hand, with a gear secured to a connecting rod to allow movement to be transmitted between the piston and said connecting rod.
The mechanical transmission device according to the present invention comprises a piston which consists of a thick disk secured on one of its faces to a support leg.
The mechanical transmission device according to the present invention comprises a support leg which has a finned structure having a flared profile, the widest part of which faces toward the face of the disk, fins uniformly distributed about its periphery to allow the piston to be cooled, and a mounting block.
The mechanical transmission device according to the present invention comprises a mounting block which at its middle and over its height has a vertical slot which lies in the continuation of the support leg.
The mechanical transmission device according to the present invention comprises a mounting block which on each side of the slot has, on the one hand, in a vertical plane a bearing face and, on the other hand, in a horizontal plane parallel to the one containing the disk, a thrust face.
The mechanical transmission device according to the present invention comprises a rack which is connected to the piston by a link rod of T-shaped cross section, which is fixed into the mounting block.
The mechanical transmission device according to the present invention comprises a link rod which has a first web which penetrates the vertical slot of the mounting block to such a point that the hole formed in said web collaborates with the bore to allow a screw to pass through said mounting block and collaborate with a tightening nut.
The mechanical transmission device according to the present invention comprises a link rod which has a second web perpendicular to the first and which bears against the face of the mounting block.
The mechanical transmission device according to the present invention comprises a rack which consists of two independent elements forming half racks which are fixed one on each side of the first web of the link rod.
The mechanical transmission device according to the present invention comprises two half racks, each of which in its upper part has a face which comes into contact with the thrust face of the mounting block.
The mechanical transmission device according to the present invention comprises two half racks, each of which comprises a first rack of a small size which collaborates with the rolling-bearing guide device, and a second rack of large size facing in the opposite direction to the first, to collaborate with the gear that transmits movement between the piston and the connecting rod.
The mechanical transmission device according to the present invention comprises a rolling-bearing guide device which consists of at least one roller which provides frictionless guidance of the half racks on the engine block.
The mechanical transmission device according to the present invention comprises a rolling-bearing guide device which consists of at least one roller which provides frictionless guidance of the half racks on the engine block, and of a gearing device which allows the displacement of said roller with respect to the piston to be synchronized.
The mechanical transmission device according to the present invention comprises a rolling-bearing guide device which consists of synchronized rollers which provide frictionless guidance of the half racks on the engine block, and of a gearing device which allows the displacement of said rollers with respect to the piston to be synchronized.
The mechanical transmission device according to the present invention comprises a rolling-bearing guide device which consists of synchronized rollers which provide frictionless guidance of the half racks on the engine block, and of a gearing device which allows the displacement of said rollers with respect to the piston to be synchronized, and of an elastic coupling provided between said rollers and said gearing device, which allows variations in speed.
The mechanical transmission device according to the present invention comprises rollers, each of which consists of a hollow cylindrical sleeve which collaborates with the runway surface of the second web of the link rod and with a smooth plate secured to the engine block.
The mechanical transmission device according to the present invention comprises a gearing device which comprises gear wheels which are fixed to each end of the sleeves.
The mechanical transmission device according to the present invention comprises gear wheels which collaborate with the small-sized racks of each half rack and with a piece the longitudinal ends of which have a rack.
The mechanical transmission device according to the present invention comprises gear wheels which have a central bore which has splines collaborating with those machined at each end of a shaft which allows said wheels to be joined together at each end of the hollow cylindrical sleeve.
The mechanical transmission device according to the present invention comprises a shaft, the outside diameter of which is of dimensions which are designed so that it can pass through the interior bore of the hollow cylindrical sleeve and therewith delimit a gap so that an elastic coupling can be fitted.
The mechanical transmission device according to the present invention comprises an elastic coupling which consists of a ring provided between the sleeve and the gear wheels so that a difference in speed between the sleeve and the gear wheels does not cause premature destruction of the latter and of the racks of the gearing device.
The mechanical transmission device according to the present invention comprises rollers consisting of sleeves which roll along the face of the second web of the T-section link rod, on the one hand, and along the smooth plate fixed to the engine block, on the other hand.
The mechanical transmission device according to the present invention comprises a gear which has a truncated profile comprising, on each side of its central bore, sets of teeth collaborating respectively with the second rack of the half racks and the control rack which is mounted in a cavity, or on a guide, each formed in the engine block.
The mechanical transmission device according to the present invention comprises a gear which between the sets of teeth has a recess for accommodating the connecting rod, more specifically its small end, so that its bore collaborates with that of said gear.
The mechanical transmission device according to the present invention comprises a gear which midway across the width of each set of teeth, has a curved groove, the radius of curvature of which is centered on the point about which said gear rocks about the connecting rod.
The mechanical transmission device according to the present invention comprises curved-profile segments which are fixed inside the grooves to constitute the runway surfaces of the gear.
The mechanical transmission device according to the present invention comprises a control rack collaborating with the sets of teeth of the gear which midway across the width has a vertical and straight groove in which a segment of the same profile is fixed.
The mechanical transmission device according to the present invention comprises a gear, the segment of the sets of teeth of which runs along the edge face of the first web of the link rod, while the other segment of the opposite sets of teeth of the gear runs along the straight segment of the control rack.
The mechanical transmission device according to the present invention has a point of contact between the synchronized rollers and the face of the second web on the one hand, and the smooth plate on the other hand, which lies on the pitch radius of the gear wheels.
The mechanical transmission device according to the present invention comprises segments which constitute runway surfaces, the point of contact of which is positioned on the pitch radius of the gear.